Near Junction Integration of Vapor Chamber for Transient Thermal Performance Improvements of SiC Power Module

Abstract

Power semiconductor modules are mostly stressed when faced with large junction temperature variations, leading to failures such as bond wire lift-off and solder fatigue. This issue becomes more challenging with the implementation of SiC devices because their smaller die size reduces the thermal inertia and increases the thermal resistance. This paper explores the potential of utilizing vapor chamber (VC) through near junction integration inside a SiC power module to reduce junction temperature swings. A novel fabrication process enables the near junction integration of VC which not only acts as heat spreaders but also conducts the drain current of MOSFETs. The thermal impedance analysis in the frequency domain highlights VC's strong attenuation effect on medium frequency thermal cycles, which are particularly damaging to power modules. Two case studies are performed to evaluate the thermal performance of VC integrated module in traction inverter applications. Both simulations and experiments demonstrate the effectiveness of integrating VC: more than 33% reduction in maximum junction temperature and 44% reduction in junction temperature fluctuation. Time constant spectrum analysis further reveals that the VC module's superior thermal performance stems from its ability to minimize thermal resistance components with short time constants, a benefit that is unique to near-junction thermal management